This invention relates to inhalators in which water in a vaporizing chamber is boiled by a heater to generate vapor and, more specifically, improvements in the inhalators the ejection of generated vapor of which causes a medicinal liquid or the like inhalant contained in a suction tank sucked up and atomized for inhalation into patient's mouth to lessen his throat pain and the like.
Although not used as the inhalator, there has been suggested a steamer for generating vapor using a heater in U.S. Pat. No. 3,742,629 of E. R. Plasko dated July 3, 1973 or Japanese Patent Publication No. JP, B, 5342/1979 of S. Takakuwa et al dated Mar. 15, 1979. In the steamer of the former patent, a vapor tank of truncated conical shape is made relatively small, a nozzle is secured as extending obliquely upward at the head portion of the tank and a heater assembly is vertically erected within the tank. This steamer, however, has a problem that, because the tank is made small, water in the tank can be soon used up and thus the user must frequently supplement water into the tank every time of use. In addition, since the water supplementation is performed usually manually and it is difficult to maintain always constant the amount of supplemented water, the time required for vapor generation determined by the supplemented water amount is made variable and the time of continuous use available for each water supplementation is also made variable, so that there have been various difficulties in its practical applications.
On the other hand, in the steamer of the latter publication, a vaporizing chamber having a heater secured thereto and a water reservoir chamber are provided. The top end portion of a water pipe is coupled through a valve means to the water reservoir chamber. The pipe extends between the vaporizing and reservoir chambers and is projected downward into the vaporizing chamber. The water pipe is provided at its downward tip end with a small hole and at the circumference above the tip end with water outflow holes so as to determine the level of water supplied into the vaporizing chamber. This arrangement is advantageous in that the water level in the vaporizing chamber is determined by the water outflow holes of the water pipe and thus the time necessary for vapor generation is made constant, and that water can be continuously supplied from the water reservoir to the vaporizing chamber and thus the continuous operation time can be prolonged sufficiently, removing various problems occurred in the above U.S. Patent. However, this arrangement is still defective in that when the water level within the vaporizing chamber temporarily drops below the outflow holes of the water pipe, the amount of ejected vapor is decreased, i.e., the vapor ejection pressure is not constant but is rather varied. Therefore, this arrangement is completely unsuitable for use as the inhalator which utilizes the vapor ejection pressure to suck and atomize the inhalant from a suction tank by the Venturi effect.
In the arrangement of Japanese Patent Publication, further, the small hole provided in the tip end of the water pipe is open in the vaporizing chamber, so that the heated water may be subject to inherent convection through this hole, making impossible to realize a rapid vapor generation. In this connection, if the small hole is selected to have such a diameter that can prevent the convection, then the small hole is clogged by fur and the like and its function of adjusting the supplied water level is disadvantageously lost.